BuildLibCalls: infer allocptr attribute for free and realloc() family functions

[nikic]

Need to handle LibFunc___kmpc_free_shared as well?

[durin42]

In D123084#3473893, @nikic wrote:

Need to handle LibFunc___kmpc_free_shared as well?

No, for two reasons:

1. The attributes can be specified directly on the declaration in llvm/Frontend/OpenMP/OMPKinds.def (see D119583)

2. MemoryBuiltins.cpp never had any logic about __kmpc_free_shared: I can't tell if this was a bug or intentional, but what we have today matches the behavior of MemoryBuiltins.cpp.

We can do a follow-up later to add the required attributes in OMPKinds.def if you'd like.

[nikic]

In D123084#3475085, @durin42 wrote:

In D123084#3473893, @nikic wrote:

Need to handle LibFunc___kmpc_free_shared as well?

No, for two reasons:

1. The attributes can be specified directly on the declaration in llvm/Frontend/OpenMP/OMPKinds.def (see D119583)

2. MemoryBuiltins.cpp never had any logic about __kmpc_free_shared: I can't tell if this was a bug or intentional, but what we have today matches the behavior of MemoryBuiltins.cpp.

The reason I asked is that this function is currently listed in https://github.com/llvm/llvm-project/blob/5ee0123642fee177258b0fd99f3fd659be68de60/llvm/lib/Analysis/MemoryBuiltins.cpp#L470. Is it non-functional for some reason?

[durin42]

In D123084#3475301, @nikic wrote:

In D123084#3475085, @durin42 wrote:

In D123084#3473893, @nikic wrote:

Need to handle LibFunc___kmpc_free_shared as well?

No, for two reasons:

1. The attributes can be specified directly on the declaration in llvm/Frontend/OpenMP/OMPKinds.def (see D119583)

2. MemoryBuiltins.cpp never had any logic about __kmpc_free_shared: I can't tell if this was a bug or intentional, but what we have today matches the behavior of MemoryBuiltins.cpp.

The reason I asked is that this function is currently listed in https://github.com/llvm/llvm-project/blob/5ee0123642fee177258b0fd99f3fd659be68de60/llvm/lib/Analysis/MemoryBuiltins.cpp#L470. Is it non-functional for some reason?

Huh. I could have sworn that wasn't there, but I even edited it. Well, fixed by adding D124491 :)

[nikic]

LGTM

[xbolva00]

Missing description (some bigger context or RFC why you need this, future plans with it, etc)

[nikic]

@xbolva00 This is part of https://discourse.llvm.org/t/rfc-attributes-for-allocator-functions-in-llvm-ir/61464. @durin42 You might want to link to that in the description of this patch series.

llvm/lib/Transforms/Utils/BuildLibCalls.cpp

 
 static bool setAlignedAllocParam(Function &F, unsigned ArgNo) {
   if (F.hasParamAttribute(ArgNo, Attribute::AllocAlign))
     return false;
   F.addParamAttr(ArgNo, Attribute::AllocAlign);
   return true;
 }
 
+static bool setAllocatedPointerParam(Function &F, unsigned ArgNo) {
+  if (F.hasParamAttribute(ArgNo, Attribute::AllocatedPointer))
+    return false;
+  F.addParamAttr(ArgNo, Attribute::AllocatedPointer);
+  return true;
+}
+
 static bool setAllocSize(Function &F, unsigned ElemSizeArg,
                          Optional<unsigned> NumElemsArg) {
   if (F.hasFnAttribute(Attribute::AllocSize))
     return false;
   F.addFnAttr(Attribute::getWithAllocSizeArgs(F.getContext(), ElemSizeArg,
                                               NumElemsArg));
   return true;
 }
case LibFunc_mktime:
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotThrow(F);
     Changed |= setWillReturn(F);
     Changed |= setDoesNotCapture(F, 0);
     return Changed;
   case LibFunc_realloc:
   case LibFunc_vec_realloc:
   case LibFunc_reallocf:
+    Changed |= setAllocatedPointerParam(F, 0);
     Changed |= setAllocSize(F, 1, None);
     Changed |= setOnlyAccessesInaccessibleMemOrArgMem(F);
     Changed |= setRetNoUndef(F);
     Changed |= setDoesNotThrow(F);
     Changed |= setRetDoesNotAlias(F);
     Changed |= setWillReturn(F);
     Changed |= setDoesNotCapture(F, 0);
     Changed |= setArgNoUndef(F, 1);
case LibFunc_fdopen:
     return Changed;
   case LibFunc_feof:
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotThrow(F);
     Changed |= setDoesNotCapture(F, 0);
     return Changed;
   case LibFunc_free:
   case LibFunc_vec_free:
+    Changed |= setAllocatedPointerParam(F, 0);
     Changed |= setOnlyAccessesInaccessibleMemOrArgMem(F);
     Changed |= setArgsNoUndef(F);
     Changed |= setDoesNotThrow(F);
     Changed |= setWillReturn(F);
     Changed |= setDoesNotCapture(F, 0);
     return Changed;
   case LibFunc_fseek:
   case LibFunc_ftell:

llvm/test/Transforms/InferFunctionAttrs/annotate.ll

 declare i32 @fputc(i32, %opaque*)
 
 ; CHECK: declare noundef i32 @fputs(i8* nocapture noundef readonly, %opaque* nocapture noundef) [[NOFREE_NOUNWIND]]
 declare i32 @fputs(i8*, %opaque*)
 
 ; CHECK: declare noundef i64 @fread(i8* nocapture noundef, i64 noundef, i64 noundef, %opaque* nocapture noundef) [[NOFREE_NOUNWIND]]
 declare i64 @fread(i8*, i64, i64, %opaque*)
 
-; CHECK: declare void @free(i8* nocapture noundef) [[INACCESSIBLEMEMORARGMEMONLY_NOUNWIND_WILLRETURN:#[0-9]+]]
+; CHECK: declare void @free(i8* allocptr nocapture noundef) [[INACCESSIBLEMEMORARGMEMONLY_NOUNWIND_WILLRETURN:#[0-9]+]]
 declare void @free(i8*)
 
 ; CHECK: declare double @frexp(double, i32* nocapture) [[NOFREE_NOUNWIND_WILLRETURN:#[0-9]+]]
 declare double @frexp(double, i32*)
 
 ; CHECK: declare float @frexpf(float, i32* nocapture) [[NOFREE_NOUNWIND_WILLRETURN]]
 declare float @frexpf(float, i32*)
 

 declare void @qsort(i8*, i64, i64, i32 (i8*, i8*)*)
 
 ; CHECK: declare noundef i64 @read(i32 noundef, i8* nocapture noundef, i64 noundef) [[NOFREE]]
 declare i64 @read(i32, i8*, i64)
 
 ; CHECK: declare noundef i64 @readlink(i8* nocapture noundef readonly, i8* nocapture noundef, i64 noundef) [[NOFREE_NOUNWIND]]
 declare i64 @readlink(i8*, i8*, i64)
 
-; CHECK: declare noalias noundef i8* @realloc(i8* nocapture, i64 noundef) [[INACCESSIBLEMEMORARGMEMONLY_NOUNWIND_WILLRETURN_ALLOCSIZE:#[0-9]+]]
+; CHECK: declare noalias noundef i8* @realloc(i8* allocptr nocapture, i64 noundef) [[INACCESSIBLEMEMORARGMEMONLY_NOUNWIND_WILLRETURN_ALLOCSIZE:#[0-9]+]]
 declare i8* @realloc(i8*, i64)
 
-; CHECK: declare noalias noundef i8* @reallocf(i8* nocapture, i64 noundef) [[INACCESSIBLEMEMORARGMEMONLY_NOUNWIND_WILLRETURN_ALLOCSIZE]]
+; CHECK: declare noalias noundef i8* @reallocf(i8* allocptr nocapture, i64 noundef) [[INACCESSIBLEMEMORARGMEMONLY_NOUNWIND_WILLRETURN_ALLOCSIZE]]
 declare i8* @reallocf(i8*, i64)
 
 ; CHECK: declare noundef i8* @realpath(i8* nocapture noundef readonly, i8* noundef) [[NOFREE_NOUNWIND]]
 declare i8* @realpath(i8*, i8*)
 
 ; CHECK: declare noundef i32 @remove(i8* nocapture noundef readonly) [[NOFREE_NOUNWIND]]
 declare i32 @remove(i8*)